A semiconductor laser is typically fabricated by depositing one or more layers of material on a substrate to form a wafer, metallizing two major surfaces of the wafer, cleaving a strip of material from the wafer and then sawing the strip at right angles to the cleavage faces to form laser chips. The laser chip may be composed of a single layer of the same or different material than that of the substrate and having a different conductivity type from that of the substrate to form a single homojunction or heterojunction device, respectively. Alternatively, the chip may be composed of a pair of confinement layers with an active layer therebetween to form a double heterostructure laser as disclosed, for example, by Kressel et al. in U.S. Pat. No. 3,747,016, incorporated herein by reference. The laser chip is then typically mounted by soldering or thermocompression bonding one of the metal layers to a metal header or to a metallized ceramic body with the electrical contact being made over the entire metal layer. The second contact to the laser chip is typically made by bonding a lead wire to the second metal layer. In this case the current enters the second metal layer in a small portion of its area and flows laterally along the metal layer before entering the device. A problem arises with this second contact in that the metal layer must be thin enough so that the strip can be cleaved from the wafer but thick enough to have sufficient current carrying capacity. We have found that, particularly for high power pulsed lasers, such as that disclosed by M. F. Lamorte in U.S. Pat. No. 3,471,923, incorporated herein by reference, that a laser fabricated in this manner fails either because resistance heating of the metal layer produces an opening in the metal layer, heats the device or produces a spatially nonuniform current flow across the p-n junction.
It would be desirable, to provide a method of fabricating a semiconductor laser which reduces or eliminates these problems.